


That One's Radioactive

by faufaren



Category: Hunter X Hunter, Naruto
Genre: Crossover, Gen, Not Canon Compliant, One Shot, Reincarnation, Snakes, Torture, Zoldyck Family - Freeform, a study on orochimaru, also i didn't watch all of shippudden, but idk, could be the beginning of a series, definitely not, kind of crack, zoldyck's a+ parenting
Language: English
Status: Completed
Published: 2017-08-10
Updated: 2017-08-10
Packaged: 2018-12-13 13:19:12
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,044
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11760720
Author URL: https://archiveofourown.org/users/faufaren/pseuds/faufaren
Summary: Orochimaru is reborn as one of the Zoldyck children.





	That One's Radioactive

It isn’t abnormal for a Zoldyck child to display great amounts of genius from birth. Each member of the Zoldyck family are all geniuses in their own way in their own unique areas, after all. But Zeno has never in his numerous years of life seen genius as it is shown in his youngest grandson. 

It isn’t genius, not really. Normally Zeno wouldn’t bother to pay much attention to his son’s children barring the eldest and heir, and it had worked perfectly fine for sixteen years up until Kikyo had her fifth. 

There's nothing wrong with the first four. It’s just… the youngest. 

Logically-minded, extremely intelligent, unnervingly observant, highly skilled in analysis and deduction, physically powerful and ruthless, Kalluto Zoldyck had all the makings of a great Zoldyck child except for a few fairly large and important details. 

Because Zeno knows the stages of the mind and all of its myriad variations. He knows smart. He knows brilliant. He knows genius, has seen three generations of Zoldyck minds, and for certain, the old blood of their family genes and the traditions of their offspring's upbringing both result in quite a number of child prodigies and masterminds––

But the near-alien intellect that has always been in his fifth grandson is nothing like inborn talent or natural brilliance, although those are there, too. The child doesn’t only catch on to theories and abstract concepts extremely well, but he also understands them with the comprehension of someone with twenty times the experience than someone his age. 

Something somewhere in Kalluto’s development has gone very seriously awry––but all in the ways that aren’t bad. (They aren’t good either, exactly.) 

From the moment he was born, Kalluto Zoldyck has exhibited an unprecedented sense of independency. Bad with authority, bad with the social hierarchy, bad with anything that tries to control him––he certainly understands orders and missions and line of command but shows no real intent to follow them. It was, according to Silva Zoldyck, a disgrace for one of their family’s blood. 

As he grows older, they soon discover his extreme curiosity. It appears in his eagerness to learn, to accumulate information as much and as fast as possible. He soaked up data like an infinite sponge, near-obsessive in the pursuit of knowledge and understanding everything completely and utterly thoroughly from the inside and out. (Curiously enough, he seems to already know most things, most of it being… _severely questionable_ ). 

By the time he was four––right in the middle of his torture immunity training––Kalluto had developed a keen fascination with the living organisms that lived around the territory of Kukuroo Mountain. 

After his fifteenth ‘research experiment’, Silva grew tired of seeing bloody dinner knives and needles filched from his eldest son and the dead entrails of some unidentifiable creature lying about his estate, and assigned a section of the basement in the east wing of the manor to Kalluto for his personal use. 

No one misses how after that, all the science experiments and ‘specimens’ and bottles of mysterious nefarious liquids immediately vanish from around the manor, almost as if it had been part of a plan all along. 

Kalluto goes missing for weeks at a time now. Well, his relatives said, at least it wasn’t anime and hentai merchandise like it is with Milluki. Although, as the experiments become more and more grotesque and horrifying, they aren't quite so sure after all. 

When he began bringing snakes into the house, the rest of them try to discourage it at first, try to stamp it out of him. This is only before they realize, much to their growing horror, that no, Kalluto isn’t going soft in the heart and adopting pet baby snakes––he’s training them. He’s raising them and then shaping them into weapons of his own, lethal servants to do his bidding, for espionage and assassination and literally anything else. They become his eyes and his ears; through his beloved snakes, Kalluto will know anything that happens in the manor. 

None of them will ever look at snakes the same way again. 

Everyone in the Zoldyck household is constantly on the lookout for the telling hiss, the slide of scales across surfaces, the slippery sheen of a snake’s diamond coat, anywhere and anytime. Even outside the estate or on missions they’re eyeing snakes suspiciously and wondering whether it is one of Kalluto’s or not, not willing kill any of them at all, just in case. 

He keeps collecting them. At five, he had twenty. A year and a half later, none of them know exactly how many snakes he has in his possession. 

When he starts talking to them, they're not even surprised anymore.

* * *

The Zoldyck matriarch specializes in poison, and takes great pride that one of her children shows the same aptitude that she does for it. 

(In fact, he's so well suited, such an affinity seems a little unnatural, a little scary.) 

Never in any of the previous generations had any child acclimated to the Zoldyck tradition of poison resistance training so quickly and so thoroughly. And the rate of it seemed to increase exponentially as he grew older. Kalluto was immune to arsenic by the age of two, mustard gas at four, ricin at five, and is drinking cyanide like water at the age of six. 

All Zoldyck members have always been odd characters in societal views, and Kalluto Zoldyck is no exception. Except, perhaps, for the fact that he is strange even for Zoldyck standards.

* * *

Over time, Kalluto’s private chamber in the basements of the manor’s east wing, where he performs his experiments and stores his specimens, gets a couple upgrades. He’s expanded; slowly claimed his territory until the entire east wing’s underground sublevel is his. Every wall and every door, even the ceilings, are heavily soundproofed. 

People can go inside but no one is willing to anymore, not after the first handful of casualties in there. Sometimes he spends days and even weeks in there, having his meals delivered to the door by the staff, and when he eventually emerges from the dark depths, no one asks about the mysterious stains and other unknown substances on odd parts of his clothes . 

There was one time when curiosity had finally won over his siblings and Killua had stolen a journal from his little brother’s bedroom––one of hundreds, arranged neatly on towering bookshelves, filled to brimming with what looks to be scientific notes and observations, theories and hypotheses and incredibly detailed diagrams. 

They discover that none of them can read it at all, that Kalluto writes all of his notes in code––a rather pretty script full of quick strokes and sideways slashes, the characters looping and blending into each other when Kalluto wrote too fast, until it seemed as if one can pull on one end of a sentence and have it all unravel as a single continuous line, like knitted yarn. 

It doesn’t look like any of the codes they learn in the household, nor any other language they can find through either the vast archives of the Zoldyck library or online database. Kalluto writes in a strange, made-up entirely undecipherable language that even Milluki, with all his thousands of memorized codes and photographic memory, gave up on cracking after a month of effort.

* * *

The staff and butlers of the Zoldyck household all know to tread carefully around Kalluto Zoldyck, because they’ve all heard of the strange disappearances of foolish or disloyal staff members, and the chilling noises that sometimes come from the east wing of the manor, even though they all knew his private chambers were soundproofed with the most advanced technology there was. 

They know that Kalluto carries multiple snakes on his person at all times, often hissing and murmuring quietly to the ones coiled around his thin shoulders in his own version of communication with them (sometimes, they think they even hear the snakes hiss back to him, as if in a conversation, but that’s ridiculous). 

They know that he has a habit of sometimes taking naps in warm sunny places, and that, after one unfortunate and very messy incident, he doesn’t like being woken up. They’ve learned that his preferred manner of sleeping is to make a giant nest of pillows and blankets in the corner of his bed and burrowing deep into it; sometimes the staff makes it for him, having memorized exactly how he likes it to be arranged, and when it’s done correctly Kalluto is pleased with them as someone would be pleased with a dog for doing a trick particularly well. 

(He’s become something of a living urban legend amongst the staff, tales about him used to frighten new additions. Recruits are sent to clean his room as a trial of entrance, wash his laundry for punishment. Casualties have occurred.)

* * *

Sometimes they all wonder about his eyes––fool’s gold and slitted like the snakes he loves so much, like his father’s cat-slit eyes but thinner, the irises much too metallic to be anything feline. 

They have no idea where it had come from. Because while Kikyo’s loyalty to her husband is undoubtedly unquestionable, all the other Zoldyck children had either a combination of their parents’ features or leaned toward one than the other. And then there’s Kalluto, who somehow comes out with a pair of piercing golden eyes that had never shown up in the family’s entire history of genes. 

Kalluto Zoldyck has slowly but steadily asserted himself as a predator in the household, subtly terrorizing his brothers and the staff into submission without even trying, escaping his father’s biological authority on him and his mother’s smothering affection before they even had the chance to exert any of it over him (and whenever he obeyed it was more like he was allowing it, instead of the other way around; the cool, knowing glint in his snake-slit eyes is always there, always knowing that he is better than all of _this_ ).

Perhaps not so surprisingly, the youngest Zoldyck child turns out to be a master at interrogation by the age of seven, the best of his siblings, besting even Milluki for all that he had nine years on him. 

Because for all of their whips and chains and electric chairs, at seven years Kalluto has taught himself the art of psychological torture and how to moderate between cruelty and kindness in just the right quantities, to hurt and take away with kindness until the victim has nothing left. 

“Don’t be afraid,” he murmured softly into the man’s ears. His words came out like silk, lazy, languid, effortless—the audiogenic version of poisoned honey. The prisoner, strapped to a metal chair and shaking terribly, stared at the child with wide eyes (he didn't stand a chance). “I’m not going to kill you. We still have so much to learn from you, and besides, I think that people are so much more useful alive than dead.” 

He slid the flat of the scalpel lovingly down the cheek of the prisoner, down to his jawline, then to the major artery at the side of his neck, not quite cutting but the danger still there. He traced random patterns on the skin, cold gold eyes watching from under lowered lids as the doodles bloomed crimson on it. 

“The human body is amazing. Despite all the ways to kill a person that I know, it actually is not an easy thing to do. The human body is a tenacious thing—frail, but tenacious. I can beat you bloody and you still wouldn’t die, not unless I break you in… certain places.” He taps the back of the blade on the exposed nape of the man's neck. 

“Here––here is one such spot, deep inside is your vertebrae, your lifeline. Now if I bring my knife in just so....” 

“Klaymor,” was what the man said, after a week of silence, staring at the small seven year-old kid with a mixture of weary terror and helpless adoration. “He’s the one.” 

“Well,” Kalluto replied and smiled, slow and heartless, like the pleased predator, as he set down the sledgehammer. “Now we’re getting somewhere. Tell me about this Klaymor.” 

It's honestly frightening even to the others, how easily their youngest is able to dismantle and take apart a man, piece by piece, sinew by sinew, and rewire and reprogram the human mind and turn it in his favor so completely and thoroughly. 

The youngest Zoldyck child, if he were just a few years older, is probably the most frightening one of them all.

* * *

It’s nice to have a mother again. Kalluto Zoldyck has the best relationship with Kikyo out of all his four siblings because Orochimaru has always favored his mother over his father. 

Orochimaru’s clan has had a long-lasting, ancient bond with snakes dating back before Konohagakure had even been founded, long before the great clan wars. The bond is displayed in their pale skin, so pale it’s nearly unnatural, their slit gold eyes, their tall and willowy frames and the androgynous appearance of both male and females of the clan, their natural immunity to various poisons, the bruise-purple clan markings––Orochimaru’s clan had been known for their distinctive looks, for certain. 

But in Konoha, as the only thing that remained of his once-great clan, Orochimaru had been shunned for his looks, ostracized for his mentality. 

Snakes are commonly known to be agender, and Orochimaru has never really minded taking the female role in espionage and infiltration missions in his old life, back when he was still loyal his Konoha and still took missions. It’d been a given, if the mission parameters had called for two females and one male, and you were in a team where the only other option was _Jiraya._

So when Kikyo took her youngest and began dressing him up as her pretend daughter (with five sons, it’s no wonder that she did), Orochimaru hadn’t felt much discomfort, going around wearing pretty kimonos and yukatas. It felt strangely familiar. His first mother had done the same, though for different reasons. 

(“Strength comes in different packages,” he remembers his mother once telling him, so long ago. “Women may not be as physically strong, but we are able to endure more pain. We may be often looked down upon by others but we can go places that men will never be able to step foot in. Men might be able to crush us instantly in brute force combat, but with a pretty dress and our wiles, we could kill them before they even realize it. Glory? Honor? We are not the samurai of Iron Country, we are shinobi and kunoichi. Our true strength lies not in flashy fights or great explosions, but in our ability to be the shadow that no one notices, the silent heart attack that no one suspects.”) 

In fact, he goes and even adopts the feminine wiles, graceful, swan-like movements worthy of a high-court geisha––while Kikyo is overjoyed, this seems to disturb most of the other members of the family a great deal, though they eventually get used to it. 

Orochimaru, as Kalluto, thinks that his new older siblings are simply darling. 

Deeply traumatized, emotionally stunted, highly powerful children with enough psychological issues to fill an ocean––they remind him so much of the little ones he used to take into his home, where he’d train and equip them––back in his old life. He’d look for the interesting ones, the powerful ones, add the ones that catch his fancy to his collection like pretty marbles and watch them grow into lethal weapons, no less screwed in the mind than when they first arrived at his lair years ago, possibly made worse by twisted ideals of fellowship and family they had no real understanding of. _(Love compels cruelty to those who do not understand love.)_

Illumi believes that Kalluto should take more missions more often, focus on training and being a profit to the family household than playing with whatever he had in that basement of his, choosing primarily to ignore him in favor of doting over Killua, as Kalluto had not much significance to the family, being the youngest born child. 

Milluki, truthfully, is a little afraid of his youngest brother; Kalluto’s always been a creepy little brat, and Milluki prefers to have as little interaction with him as possible (he already has minimal interaction with his family anyway, it wouldn't make much of a difference). 

Alluka hasn’t had much interaction with Kalluto at all, as he is kept far away from his younger brother, due to Kalluto's infamous habit of dissecting anything that catches his fancy (and Alluka, indeed, is very, very _fascinating_ ). 

Killua also thinks that Kalluto is creepy and very possibly insane, and maybe panders to their mother just a bit too much, but likes him more than his other siblings at least, with the exception of Alluka. 

Once, Kalluto returned to his room only to find Killua snuggled into his pillows and blankets smelling of blood and death and pain, though there is no visible evidence on him. 

“Being with Illumi sucks,” Killua told him, voice muffled into the pillow he clutched. “You… your pillows are fluffier.” 

(In turn, Orochimaru likes Killua the best out of his brothers… perhaps the similarities between Mitsuki and Killua playing a large factor in that.)

* * *

In this world, there is no chakra. Instead, there is Nen. 

A person would think that Nen and chakra are essentially one and the same except that then they would be wrong. Most people live their entire lives without learning about the hidden well of power stored in every person’s being, but when Orochimaru was born into this world the first thing he noticed once he became capable of rational thought was the strange mist of energy that hovered over his skin like a cloak. 

He had been very Confused, then. It was a whole other level from normal confusion. On a scale of ‘where is my cat?’ to ‘where did all my clothes and money go?’ he felt he was experiencing the equivalent of ‘what manner of cosmic astro-material is swimming in my veins now?’ 

None of his jutsus and seals work anymore, no matter what he draws on the parchment or what signs he shapes his fingers into. There aren't any techniques or releases but rather these properties called Ten, Ren, Hatsu, and Zetsu. There aren't any elemental attributes anymore but things called enhancers, conjurers, transmuters, and so on. 

Nen has other applications as well, once he gets used to the idea of it. (And he finds that some uses are quite similar to chakra, and that's… well. It's a comfort.) 

Kalluto Zoldyck turns out to be a manipulator, to no one’s surprise.

* * *

From the back Silva Zoldyck looks so strikingly similar to Jiraya that Orochimaru almost mistakes him for his former squadmate when he first sees his new father for the first time, much to his abject horror. 

But no; once the man turned around all the similarities are erased, the differences are too many and too drastic. Silva’s cold, calculating silent demeanor is absolutely nothing like what Jiraya had been––a fire, so alive and so warm, so brilliant that he burned.

* * *

“What are you?” 

It’s one afternoon after Kalluto had returned from a mission (a simple assassination, so easy he could have done it in his sleep) and was writing in his journal in his bedroom, an experiment in progress sitting patiently next to him. Killua lounged in the couch across from him, playing one of his video games. The rest of the family have gone, disappeared off to their own respective assignments. 

Kalluto glances over his shoulder, seems amused by the question. “What do you mean?” he asks back, voice sweet and laced with false innocence. 

Killua rolls his eyes, losing interest in his game as he looks carefully at his youngest brother. You know what I mean. People are starting to talk. Have been talking.“

“People are always talking, that’s what people do,” Kalluto says. “About what is where it sometimes differs. What’s the issue?” 

“You’re the issue. Dad says we should stay away from you, even though you’re one of us. Why though? You’re…” 

“Me…?” Kalluto’s watching him with those odd gold eyes, ones that Killua had always thought were kind of pretty even though it shouldn’t really be. 

Killua stares at him in silence for a little while more before saying, “You’re just weird,” and returned to his game. 

“Is it causing you trouble? Spending so much time with me?” Kalluto was alone most of the time, being a naturally solitary creature. It was, however, pleasant to have another’s company every once in awhile. 

“Hm.” Killua made no comment, but Kalluto could see the frown forming on his face. 

“You know you don’t have to keep associating yourself with me. Go spend more time with Alluka.” Kalluto said after a moment, unusually solemn and sympathetic. “I know Father and Illumi have been giving you a hard time about this.” 

Killua, surprised, turned flustered. “It’s nothing I can’t handle,” he scowls even more, as if it would give the statement more substance. Then, quietly he added, “Besides, I… don’t want you to be lonely.” 

The long buried father/mother instinct that Orochimaru had developed in his previous life lurches within him and he bites his lip in order to stop himself from, gods forbid, cooing at Killua. Instead he says, “Well, regardless, if you ever need my assistance in dealing with them, I’m here to help.” 

Strangely enough, Killua looked mildly worried. For his family. “I think I’m good.” 

He looks over at what Kalluto was currently working on at his workstation, pausing his game and sitting up. “What are you doing right now?” 

“Just a project I’ve been putting off for a while until now. I figure I might as well finish it up,” Kalluto tells him. He turns more lively, as he always does when it comes to his scientific passions. “I’m trying to figure out a way to mass-synthesize something of the six-legged jack rabbit that lives on the outskirts of Mount Kukuru. They have a special gland at the base of their brain, you see, that produces a substance whose chemical properties causes the body to generate an excessive amount of energy in times in which its life is placed in danger, thus allowing for actions that couldn’t have been physically possible otherwise. Of course, the after effects are somewhat detrimental, since the body is forced to do things beyond its physical capabilities…” 

(It was better known as the soldier pill, in Orochimaru’s old world. Or at least an extreme version of it. Perhaps the kind that Konoha Akimichi clan developed for their techniques.) 

He pokes at the rabbit, pinned to the cutting board, its head split apart and laid open for all to see the delicate brain tissue and intricate network of nerves and veins inside. He twitters in excitement. “The utter ingenuity of it, the brilliance of its biology designed to sustain its minimal functionality for survival after such an excessive influx of energy––It’s simply beautiful. Beautiful.” 

He all but sighs in contentment, as he focuses on lifting the delicate neural connections out from the rabbit’s spine. Behind him, Killua makes a sound of disgust. 

“I can’t believe I have _such_ a weirdo for a baby brother.”

* * *

So many not-quite parallels from this life to his previous one, connections only he can see and half-faded ghosts of friends in strangers he meets, memories of another world never forgotten, and of course it would make sense for Orochimaru to join this world’s answer to the Akatsuki organization. 

The Genei Ryodan really should have made him uneasy, more than a little suspicious. But no, there is no hidden agenda, no convoluted plan for world domination, no greater-than-life motive to this peculiar group. Its leader is just their leader, no dark figure in the shadows puppeteering events and incidents, no manipulations or deceit, just a leader––and what a leader they have. 

Kuroro Lucilfer is refreshing. This is a man who has assembled an arsenal of the most powerful and most dangerous people in the world, all of them willing to follow him to the ends of the earth, merely because he could. 

For all they are polar opposites, it makes Orochimaru think of what could have happened if Naruto Uzumaki had gone just a little wrong, his direction a slight bit off, something somewhere in his personality or his development or his temperance that could have directed that endless fount of charisma into––something else. To be honest, of all the infinite number of things that could have easily gone astray, especially considering the boy’s childhood and the power he held, the fact that none of those things happened with Naruto was nothing short of a miracle. 

“Kalluto, tell me what you’re thinking?”

Kalluto glances over and there’s Kuroro Lucilfer, staring back with inquisitive gray eyes. “I’m thinking…” Kalluto hums in thought, taking his time in replying, “that you’ve read that book for perhaps the fifth time this week.” 

Kuroro looks down at the thick tome he held in his hands as if just realising he had it. “I can’t help it,” says he, sighing forlornly. “We’re in between missions. The others are out each to their own businesses and there’s nothing else better to do.” 

“How about going on another stealing-murdering spree at the black markets?” Kalluto suggests. 

“I’ve done that twice in the past two days. Won’t you join me this time?” 

“Hmm,” considers Kalluto. “I would if I needed more specimens. At this time, I don’t. So, no.” 

“Alas.” 

“How about another book?” Kalluto was really feeling as if he had been transported back to his old life, listening to one of the children at his underground base complain about the lack of things to do, other than to train. 

“There is only so many grand libraries one can rob before one has read everything there is to read.” 

Kalluto raises his eyebrows, impressed, though not quite surprised. “Even so,” he says, “the pursuit of knowledge is never finished.” 

“True. You seem to be quite familiar with these matters, Kalluto,” says Kuroro. “Though we seem to differ widely in methods. You seem to prefer to wade in the guts of dead creatures, rather than the pages of a book.” 

“It’s not that I don’t like reading,” Kalluto frowns, thinks of the frustration he’d felt when he had started scouring the world’s libraries and databases for knowledge at the ripe age of four and had discovered nothing but information he had already known, had studied extensively himself in another life, and the words are out of his mouth before he thought about them more carefully––“I just find the books of this world rather underdeveloped.” 

Kuroro sits up, eyes locked onto the young boy with an eery amount of sudden interest at those words. “‘This world?’” he asks. 

Kalluto gazes steadily back at the man, studying him and his eyes, thunder grey in color and so very young with the raw curiosity and wonder at the world that only those filled with the blitheness of youth can have. Kalluto, who remembers an entire life before this one, an entire other world, who has fought in and endured generations of war and brutality, feels heavy and prosaic in comparison, like a blade dulled with the overuse of life. 

Suddenly, he misses it. Them. The people he had once allowed to come close to his heart before he lost them all, lost them twice when he was reborn in this strange foreign world. There had been nothing for him here except for the wealth of new things and potential study subjects, and that and the drive for knowledge he had been relieved to find unaltered had been what lasted him through the years––the same mad fervor he remembers plunging into those decades he had spent apart from the village hidden in the leaves and those he had come to care for inside it, so few out of the thousands but so very precious. 

(Once again he had become the cold, inhuman scientist he always had the capacity of becoming after there had been no one left to nurture that other warmer, smaller side of him, no one to draw the lines for him or to guide him back from the path of obsession. Fleeting glimpses of people he’d once known in the characters presented to him in this second life only made the ache more noticeable, more difficult to ignore.) 

“Yes,” says the man once called Orochimaru, and his words had turned strangely sibilant, some consonants elongated and slurred together, the ancient mythical accent of the language of the snakes that his old clan had kept alive within their bloodlines for centuries before he had been the only one left remaining of them. 

Suddenly, backlit by the weak orange light streaming in through the cracked windows of the warehouse, dust motes swimming lazily in the fading sun, the boy seems decades older. It’s in the shadows tracing his eyes, bruise-purple and oddly sharp in appearance; in the silky head of midnight hair, so untouchably dark in its hue that light seemed to slide right off of it; in the sickly pallor of his skin and the way his veins were displayed in an intricate webwork of blue and purple at his inner arms, near his neck. His shoulders hunch in on himself, rigid in the midst of memories of a time long gone past and sorrow and the bitterness of an age that was not presented in the appearance of the young boy in front of Kuroro. 

“Ah…” Kuroro nods like he understood, but his eyes still gleamed with an unsatisfied interest. “I see.” 

Orochimaru smiles, and it was not a pretty smile. “No, you don’t.” he says. “And I don’t expect you or anyone else to be able to figure it out.” 

“I will,” Kuroro replies, feeling inexplicably childish in his defiance of an eleven-year-old. “Just stick with me and eventually, I’ll figure it out.” 

“Take your time,” says Orochimaru.


End file.
